Lubricant for use in press working of a metal material and a press working method of a metal material using the same

ABSTRACT

A non-chlorine type lubricant in which a sulfur type extreme pressure additive, an organic zinc compound, a calcium type additive, and an ester compound are blended with a base oil for the lubricant, and having a kinetic viscosity from 5 to 50 mm 2 /s at 40° C.

BACKGROUND OF THE INVENTION

The present invention concerns a non-chlorine type lubricant for use in press working of metal materials. Specifically, it relates to a lubricant suitable to press working of metal materials that are to be used as parts, such as oil filter cases, applied with a coating treatment after press working. Further, it relates to a press working method of metal materials using the lubricant.

Upon press working of a metal material, a lubricant is generally supplied between a tool and the metal material. This is for avoiding occurrence of cracks or seizing in a work due to insufficient lubrication or deterioration of a working life of a die due to increase of friction. In shearing as a sort of the press working, a metal material is fabricated by punching it using a die and a punch. Accordingly, in a shearing process such as fine blanking (FB working), larger stresses are generated between the tool and the metal material than that in other pressing or machining process. Therefore, an extremely high anti-seizure performance or lubrication performance is required for a lubricant used in the shearing.

Lubricants with addition of chlorine type additives high in lubricity have been used. However, for when using a chlorine type lubricant, a problem can occur when the ingredients of the chlorine type additives in the lubricant decompose during working or after working with time causing rust in the metal material or the tool. Further for the chlorine type lubricant, a problem can occur by causing generation of deleterious substances or corrosion, damages, etc. to incineration furnace during incineration.

In view of the above, JP-A Nos. 2002-155293 and 8-20790 disclose lubricants as non-chlorine type lubricants. However, such lubricants are used in machining and still leaves the above stated problems in view of the seizure resistance or the lubricity of lubricants for use in press working of metal materials.

A metal material fabricated by using a lubricant requires subsequent degreasing and cleaning because of the lubricant. For example, a plating or coating step is further applied depending on parts, such as casings for automobile oil filters. In this case, unless the lubricant is completely degreased or cleaned (hereinafter simply referred to as cleaning) in the cleaning step, residual oil ingredients repel a coating material to cause plating spots or coating spots. Accordingly, the kinetic viscosity of a lubricant is preferably as low as possible in view of the cleaning property. The cleaning property means easy flushing of lubricant ingredients from the surface of the metal material. In a case where the kinetic viscosity of the lubricant is lower, the lubricant can be cleaned easily, and it can be cleaned favorably, for example, by merely cleaning with an alkali ion water. However, when considering the lubricity, it is preferred that the kinetic viscosity of the lubricant is as high as possible. In a case where the kinetic viscosity of the lubricant is higher, since the deposition amount of the lubricant to the surface of the metal material increases, favorable anti-seizing property or lubricity can be provided. Then, there is demand for a lubricant for use in press working of metal materials which is a non-chlorine type, gentle to environment, excellent in the lubricity, and has less negative effects on the subsequent steps such as cleaning or coating.

BRIEF SUMMARY OF THE INVENTION

A lubricant according to the present invention has a non-chlorine type composition in which (a) a sulfur-type extreme pressure agent, (b) an organic zinc compound, (c) a calcium type additive, and (d) an ester type compound are blended with a lubricant base oil. This can provide a lubricant not giving undesired effects on a tool working life and gentle to environment, as well as providing excellent lubricity and anti-seizure property. Particularly, even in a case where the kinetic viscosity of the lubricant is relatively low, satisfactory lubricity and anti-seizure property can be provided. In addition, the kinetic viscosity at 40° C. is controlled to 5 to 50 mm²/s (cSt). In a case where the kinetic viscosity at 40° C. is controlled within the range described above, since the lubricant has an appropriate fluidity, the lubricant can be cleaned easily after the working and cleaning with alkali ion water is also possible while ensuring good lubricancy and anti-seizure property also in the shearing. Accordingly, undesired effects on the subsequent steps such as plating step or coating step can be suppressed effectively.

(a) The sulfur content can be from 0.5 to 10% by weight based on the entire amount of the lubricant, (b) the zinc content can be from 0.05 to 1.0% by weight based on the entire amount of the lubricant, (c) the calcium content can be from 0.1 to 2.0% by weight based on the entire amount of the lubricant, and (d) the ester content can be from 0.1 to 2.0% by weight based on the entire amount of the lubricant.

Further, the invention can provide a press working method of a metal material including a step of conducting work while supplying the lubricant between a metal material and a tool. As the metal material, anti-rust steel sheet (preferably, electrolytic zinc plated steel sheet) is used. Shearing is applied while supplying the lubricant between the tool and the metal material. After the Shearing, the metal material is cleaned with an alkali ion water heated to 60° C. to 80° C. Then, the metal material is applied with a coating treatment. In a case where the metal material is an anti-rust steel sheet, there is no requirement to ensure high anti-rust preventing property in the lubricant thereby also avoiding an increase of the cost and increase of the viscosity of the lubricant. In a case where the alkali ion water is heated to 60° C. to 80° C., the cleaning property of the lubricant is improved. In a case where cleaning with the alkali ion water is possible, the detergent cost can be decreased and the cleaning step is facilitated.

DETAILED DESCRIPTION OF THE INVENTION

The base oil for the lubricant is not particularly restricted so long as it is generally used as the base oil for the metal processing oil, and one or more members selected from mineral oils, synthesis oils, and oils and fats can be used. As the mineral oils, those mineral oils purified by using a customary method in the lubricant production process of the petroleum purification industry can be used. Specifically, they include those formed by purifying lubricant fractions obtained through atmospheric distillation or vacuum distillation of crude oils by applying one or more processes such as solvent deasphaltization, solvent extraction, hydrogenolysis, solvent dewaxing, catalytic dewaxing, hydrogenating purification, sulfuric acid cleaning, and white clay treatment.

The synthetic oils include, for example, poly α-olefin, α-olefin copolymer, polybutene, alkylbenzene, polyoxyalkylene glycol, polyoxyalkylene glycol ether, and silicone oil. Specific examples of the oils and fats include, for example, beef tallow, lard, soybean oil, rapeseed oil, bran oil, coconut oil, palm oil, palm core oil, as well as hydrogenation products thereof. In the lubricant according to the invention, only one of the base oils can be used alone or two or more of the base oils may be used in admixture.

(a) A characteristic of sulfur type extreme pressure additives according to the present invention includes sulfur atoms, additives that can provide an extreme pressure effect, but that various additives—can be used as long as they provide similar effects. Examples of the sulfur type extreme pressure additives can include, for example, sulfurized oils and fats, sulfurized fatty acids, sulfurized esters, sulfurized olefins, polysulfides, thiocarbamates, and sulfurized mineral oils. The sulfurized oils and fats can be obtained by reacting sulfur and oils and fats (lard oil, whale oil, plant oil, and fish oil, etc.). Examples include sulfurized lard, sulfurized rapeseed oil, sulfurized caster oil, sulfurized soy been oil, etc. Examples of the sulfurized fatty acids can include, for instance, sulfurized oleic acid and sulfurized acid esters include, for example, sulfurized methyl oleate, and sulfurized octyl bran fatty acids. The sulfurized olefins can be obtained by reacting olefins of 2 to 15 carbon atoms or dimer to tetramer thereof with a sulfating agent such as sulfur or sulfur chloride.

Examples of the polysulfides include dibenzyl polysulfide, di-tert-nonyl polysulfide, didodecyl polysulfide, di-tert-butylpolysulfide, dioctyl polysulfide, diphenyl polysulfide, dicyclohexyl polysulfide, etc. Examples of the thiocarbamates can include zinc dithiocarbamate, dilauryl thiodipropionate, and distearyl thiodipropionate. The sulfurized mineral oils can be formed by dissolving elemental sulfur in mineral oils. The mineral oil type lubricant base oils exemplified in the description for the base oils can be used as mineral oils for dissolving the elemental sulfur. The sulfur type extreme pressure additives may be used each alone, or two or more of them may be used in combination.

In the invention, the sulfur content in the lubricant derived from the ingredient (a) is from 0.5 to 10% by weight, preferably, from 1.0 to 7.0% by weight and, more preferably, from 1.2 to 5.0% by weight based on the entire amount of the lubricant. When the sulfur content is less than the above range, sufficient lubricity may not satisfactorily be provided in relation with the kinetic viscosity. When the sulfur content is more than the range, it can be difficult to obtain improvement in lubricating effect in relation to the blending amount cannot be obtained, as well as the kinetic viscosity of the lubricant increases wastefully, which is not preferred.

Preferred organic zinc compound (b) includes zinc dialkyl dithiophosphate (hereinafter referred to as ZnDTP), and zinc dialkyl dithiocarbamate (hereinafter referred to as ZnDTC). ZnDTP has, for example, antioxidant property, anti-corrosion property, load durable property, and anti-wear property and are used generally for engine oils or industrial lubricants as so-called multifunction type additives. ZnDTP and ZnDTC have chemical structures analogous with each other, and ZnDTC has been utilized recently as a substitute compound capable of providing an effect equivalent with that of ZnDTP. The alkyl groups in ZnDTP and ZnDTC may be identical or different with each other. That is, in the structural formula of ZnDTP, two alkyl groups are bonded by way of an oxygen atom to a phosphorus atom, in which the alkyl groups may be identical or different with each other. Further, in the structural formula of ZnDTC, two alkyl groups are bonded to a nitrogen atom in which the alkyl groups may be identical or different with each other. Further, since the zinc atom is bonded by way of two sulfur atoms with a phosphorous atom or a nitrogen atom both in ZnDTP and ZnDTC, they also contain the sulfur content. The alkyl groups of ZnDTP and ZnDTC are, preferably, alkyl groups of 3 or more carbon atoms or aryl groups. Such organic zinc compounds may be used each alone or two or more of them may be used in combination.

In the invention, the zinc content in the lubricant derived from the ingredient (b) is from 0.05 to 1.0% by weight, preferably, from 0.1 to 0.9% by weight and, more preferably, from 0.5 to 0.8% by weight based on the entire amount of the lubricant. When the zinc content is less than the above range, sufficient lubricity may not satisfactorily be provided in relation with the kinetic viscosity. When the zinc content is more than the range, it can be difficult to obtain improvement in lubricating effect in relation to the blending amount cannot be obtained, as well as the kinetic viscosity of the lubricant increases wastefully, which is not preferred.

Preferred calcium type additives (c) include calcium sulfonate, calcium salicylate, and calcium phenate. Particularly, calcium sulfonate is preferred in view of the kinetic viscosity or the cost. A basic calcium sulfonate is more preferred. A basic calcium sulfonate with a total base number (TBN) of 300 mgKOH/g or more is further preferred. They can be alkaline earth metal salts of organic acids and added generally as a viscosity improver, and can be used appropriately as those excellent both in the lubricity and anti-rust property and capable of providing equivalent effects. Accordingly, such calcium type additives can be used each alone or two or more of them may be used in combination.

The calcium content in the lubricant derived from the ingredient (c) in the invention is from 0.1 to 2.0% by weight, preferably, from 0.2 to 1.5% by weight and, more preferably, from 0.3 to 1.0% by weight based on the entire amount of the lubricant. When the calcium content is less than the above range, sufficient lubricity may not satisfactorily be provided in relation with the kinetic viscosity. When the calcium content is more than the range, it can be difficult to obtain improvement in lubricating effect in relation to the blending amount cannot be obtained, as well as the kinetic viscosity of the lubricant increases wastefully, which is not preferred.

Preferred ester compound (d) includes, for example, polyol esters and complex esters. One of them or two or more of them may be blended with the lubricant base oil. The polyol esters are those polyol esters of aliphatic polyhydric alcohols and linear or branched fatty acids. The aliphatic polyhydric alcohol forming the polyol ester includes, for example, neopentyl glycol, trimethylol propane, ditrimethylol propane, trimethylol ethane, ditrimethylol ethane, pentaerythritol, dipentaerythritol, and tripentaerythritol. Further, partial esters of the aliphatic polyhydric alcohols and the linear or branched fatty acids described above can also be used. The complex esters are those complex esters of aliphatic polyhydric alcohols and linear or branched fatty acids, or linear or branched aliphatic dibasic acids. The aliphatic polyhydric alcohol ingredient can include, for example, trimethylol propane, trimethylol ethane, pentaerythritol, and dipentaerythritol. Further, the fatty acid ingredient can include, for example, aliphatic carboxylic acids, heptadecyl acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, and lignoceric acid. The dibasic acid can include, for example, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanoicdioic acid, carboxyoctadecanoic acid, carboxymethyl octadecanoic acid, and docosanodioic acid.

The ester content derived from the ingredient (d) in the invention is from 0.1 to 2.0% by weight, preferably, from 0.2 to 1.5% by weight and, more preferably, from 0.3 to 1.0% by weight based on the entire amount of the lubricant. When the ester content is less than the range described above, satisfactory anti-seizure property is difficult to obtain. When the ester content is more than the range described above, improvement for the effect corresponding to the blending amount is difficult to obtain and the kinetic viscosity of the lubricant increases wastefully, which is not preferred.

The lubricant containing the ingredients (a) to (d) is controlled for the final kinetic viscosity at 40° C. within a range from 5 to 50 mm²/s, preferably, from 10 to 45 mm²/s, more preferably, from 12 to 40 mm²/s and, most preferably, from 12 to 25 mm²/s. In a case where the kinetic viscosity of the lubricant is lower than 5 mm²/s, the deposition amount of the lubricant to the metal material may be insufficient, resulting in a less than satisfactory lubricity and anti-seizure property effect in the press working. In a case where the kinetic viscosity of the lubricant is higher than 50 mm²/s, deposition amount of the lubricant to the metal material increases excessively to lower the cleaning property. This may cause the lubricant to remain on the surface of the metal material in the cleaning step after the working to possibly cause coating spots due to repellency of the coating material in the subsequent coating treatment or the like. In a case where the kinetic viscosity of the lubricant is controlled within the range described above, cleaning can be conducted satisfactorily also by cleaning with an alkali ion water.

Further, for maintaining the basic performance as the metal processing oil, various kinds of known additives can be blended appropriately within a range not hindering the purpose of the invention. The additives include, for example, anti-rust agents, anti-oxidizing agents, corrosion inhibitors, colorants, defoamers, and perfumes. The anti-rust agent, for example, can include calcium type anti-rust agents, barium type anti-rust agents, and wax type anti-rust agents. The anti-oxidizing agents, for example, can include amine type compounds, and phenol type compounds. Also, the corrosion inhibitors, for example, can include benzotriazole, tollyl triazole, and mercapto benzothiazole can optionally be added properly. As the colorant, dyes or pigments can be used.

The present invention is useful and can improve press working of metal materials such as deep drawing, bending, blanking, piercing, trimming, caulking, compounding, burring, and fine blanking. Particularly, the lubricant can be used suitably to precise shearing that generates high stresses during working such as punching, blanking, trimming and piercing.

Further, the lubricant according to the invention can be used for the working, for example, of stainless steels, alloy steels, and carbon steels, as well as non-iron metal materials such as aluminum alloy materials and copper materials. Further, the form of the materials can include, for example, cold rolled steel sheets, hot rolled steel sheets, plated steel sheets, and anti-rust steel sheets, and the lubricant is preferably used for the working of anti-rust steel sheets. This is because anti-rust steel sheet has no requirement of coating an anti-rust oil after the working and it is not particularly necessary for increasing the anti-rust property of the lubricant of the invention. The anti-rust steel sheets include, for example, electrolytic zinc plated steel sheets, molten zinc plated steel sheets, electrolytic zinc-nickel alloy plated steel sheets and organic composite plated steel sheets. Particularly, the electrolytic zinc plated steel sheet is preferred in view of smooth and fine appearance at the surface, easy welding, easy coating, favorable workability and relatively low cost. The preferred metal material includes, specifically, SPH 270D-OD SM, SPH 270D-OD, SPHE-P, etc.

Further, since the lubricant of the invention is improved for the cleaning property by controlling the kinetic viscosity thereof, it is used preferably upon working the metal material as a part on the premise of applying the coating treatment after the working. So long as it is used for parts that are to be applied with the coating treatment after the working, other parts can include, for example, outer plate panel materials and oil filter cases for automobiles. The oil filter is a part of filtering obstacles, worn powder, carbon, etc. that may intrude into oils for lubricating the internal combustion engine of an automobile, that is, an engine oil. The oil filter case is a member for defining the outer shape of the oil filter which is usually fabricated into a predetermined shape and then coated with a coating material for use. The metal material used as the oil filter case includes, for example, SECD, SPCE, SECC, and SPCD.

Upon pressing the metal material, the working accuracy of the metal material is improved by supplying the lubricant of the invention between the metal material and the tool. The method of supplying the lubricant is not particularly restricted and the lubricant can be used by a known method, for example, coating to the surface of a metal material by a roller, or by coating to the surface of the metal material by spraying. Further, since rusting or damage to the tool can be prevented by supplying the lubricant of the invention between the metal material and the tool, the working life of the tool can be extended.

The post treatment step after the working of the metal material includes generally, for example, a step of degreasing and cleaning a lubricant deposited to the metal material, a step of applying countermeasure to rusting for a work by coating an anti-rust oil, a step of applying plating or coating, a step of applying a heat treatment to ensure a strength of the work, and a step of welding the metal material to other metal part. In this case, since the lubricant of the invention is controlled to a relatively low kinetic viscosity while having excellent lubricity and anti-seizure property, the lubricant can be cleaned and removed easily and reliably in the cleaning step. Accordingly, also in a case of applying plating or coating of a coating material to a metal material succeeding to the press working, a part of good quality can be produced with no plating spots or coating spots. Particularly, it provides excellent cleaning property in a case of cleaning with an alkali ion water. Further, in a case of using an anti-rust steel sheet as the metal material, the anti-rust oil coating step after the working is not necessary. For example, in a case of manufacturing an oil filter case, it is manufactured after press working of a metal material by way of cleaning step, plating step, and coating step.

(Cleaning Property Test)

For confining how the cleaning property changes depending on the kinetic viscosity of the lubricant, the following test was conducted. In this cleaning test, mineral oils at 100% purity (no additives), shown below, were used as the base oil in the invention.

Base oil 1: paraffinic mineral oil (kinetic viscosity at 40° C.: 480 mm²/s) Base oil 2: paraffinic mineral oil (kinetic viscosity at 40° C.: 350 mm²/s) Base oil 3: paraffinic mineral oil (kinetic viscosity at 40° C.: 95 mm²/s) Base oil 4: naphthenic mineral oil (kinetic viscosity at 40° C.: 46 mm²/s) Base oil 5: paraffinic mineral oil (kinetic viscosity at 40° C.: 32 mm²/s) Base oil 6: paraffinic mineral oil (kinetic viscosity at 40° C.: 20 mm²/s) Base oil 7: paraffinic mineral oil (kinetic viscosity at 40° C.: 10 mm²/s) Base oil 8: paraffinic mineral oil (kinetic viscosity at 40° C.: 5 mm²/s)

The method and the condition of the cleaning testis described below.

Cleaning water: alkali ion water Work: Shape cup-shape having a 65 mm inner diameter

Material SECD

Thickness 0.5 mm

Lubricant Supplying Method: Brush Coating

Each of the base oils were coated onto five works and after shower cleaning them with an alkali ion water heated to 60 to 80° C. for approximately 67 seconds, and the surface state was visually observed. The alkali ion water is water exhibiting alkalinity formed from city water by passing through an ion exchange membrane to remove an acidic ion content. The result is shown in Table 1. The evaluation criterion in Table 1 is as shown below in which the unit for each of the values is mm²/s.

TABLE 1 Base Base Base Base Base Base Base Base oil 1 oil 2 oil 3 oil 4 oil 5 oil 6 oil 7 oil 8 Kinetic 480 350 95 46 32 20 10 5 viscosity Evaluation X X X-Δ Δ-◯ ◯ ◯ ◯ ◯

From the result of Table 1, it can be seen a trend that the cleaning property is worsened as the kinetic viscosity is higher, and the cleaning property is enhanced as the kinetic viscosity is lower. Further, it can be seen that base oils 4 to 8 with the kinetic viscosity lower than 50 mm²/s scarcely show oil repellence also upon cleaning with the alkali ion water.

(Lubricity—Anti-Seizure Property Test)

While it could be confirmed by the cleaning property test that the cleaning property is excellent as the kinetic viscosity of the lubricant is lower, another test is performed to verify the lubricity and the anti-seizure property. To perform the test, the base oil 4, at the critical level in the cleaning property test, was selected and various kinds of additives were added thereto to evaluate the lubricity and the anti-seizure property (hereinafter both of the performances are optionally referred to collectively as “workability”).

The test conditions in this case are as follows.

Press: AIDA wring press VL-6000 (manufactured by Aida Engineering Co.)

Production speed: 70 spm

Punch 1: SKD 11, Punch 2: SKD 11+TiN coating

Dice: SKD 11

Material feed: 23.5 mm

Metal Material:

SPH 440 (440N/mm² high tensile steel sheet)

Width: 70 mm sheet thickness: 4.6 mm

Method of Feeding Lubricant:

Coating uniformly on the surface of metal material by resin roll

The kinds of each of the additives are as shown below:

(a) Ingredient

a1: polysulfide (sulfur content: 37% by weight)

a2: sulfurized oils and fats (sulfur content: 15 wt %)

(b) Ingredient

b: ZnDTP (Zn content: 9 wt %, sulfur content: 16 mass %)

(c) Ingredient

c: calcium sulfonate (calcium content: 15 wt %)

(d) Ingredient

d: polyol ester and complex ester

(Other Ingredient)

e: chlorinated paraffin (chlorine content: 50 wt %)

Lubricants prepared to compositions shown in Table 2 and Table 3 by adding each of the additives described above to the base oil 4 in the cleaning test was fed uniformly by a resin roll to the surface of metal materials. Metal materials coated with the lubricants were punched simultaneously each by using two kinds of punch 1 and punch 2 to form holes each sized 10 mL×12 mmW×4.6 mmt at two positions. Then, the state at the surface of the punch after punching and the state of the worked surface of the metal material after punching were observed visually and evaluation was conducted. Also the results are shown in Table 2 and Table 3. In Table 2 and Table 3, values other than those for the kinetic viscosity are indicated by % by weight, the kinetic viscosity is a kinetic viscosity at 40° C. on the basis of the unit of mm²/s. Further, the evaluation criterion in this case is as below.

Surface State of Punch

excellent, ◯: good, Δ: worn slightly, x: worn

State of Shearing

fine sheared surface, ◯: dull sheared surface, Δ: fractured somewhat, x: many fractured surface

When shearing the metal material, the metal material is punched by the shearing stress of the punch and the dice. In a case where the lubricity is poor, since it is in a fractured state irrespective of the shearing force, when the hole after the punching is in a shearing surface, this means good lubricity.

TABLE 2 Lubri- Lubri- Lubricant Lubricant Lubricant Lubricant Lubricant Lubricant Lubricant Lubricant Lubricant Lubricant cant cant 1 2 3 4 5 6 7 8 9 10 11 12 Base oil 60 80 90 40 70 85 75 90 95 20 60 80 a1 20 10 5 20 10 5 20 10 5 a2 20 10 5 20 10 5 20 10 5 b 20 10 5 20 10 5 c 25 10 5 20 10 5 d Total 100 100 100 100 100 100 100 100 100 100 100 100 Sulfur 10.40 5.20 2.60 13.74 6.87 3.44 14.02 7.01 3.51 content Zinc 1.78 0.89 0.45 1.78 0.89 0.45 content Calcium 3.80 1.52 0.76 3.04 1.52 0.76 content Ester content Kinetic 90 63 53 118 72 57 85 58 51 198 94 65 viscosity State of ◯ ◯ Δ ◯ ◯ Δ ◯ Δ X ◯ ◯ Δ punching State of ◯ ◯ Δ ◯ ◯ Δ ◯ Δ Δ-X ◯ ◯ Δ worked surface

TABLE 3 Lubricant Lubricant Lubricant Lubricant Lubricant Lubricant Comp. Comp. Comp. 13 14 15 16 17 18 Example 1 Example 2 Example 3 Base oil 19 17 15 59 57 55 50 75 90 a1 20 20 20 10 10 10 a2 20 20 20 10 10 10 b 20 20 20 10 10 10 c 20 20 20 10 10 10 d 1 3 5 1 3 5 e 50 25 10 Total 100 100 100 100 100 100 100 100 100 Sulfur content 14.02 14.02 14.02 7.01 7.01 7.01 Zinc content 1.78 1.78 1.78 0.89 0.89 0.89 Calcium content 3.04 3.04 3.04 1.52 1.52 1.52 Ester content 1.00 3.00 5.00 1.00 3.00 5.00 Chlorine content 25.00 12.50 5.00 Kinetic viscosity 212 244 281 101 116 133 101 67 52 State of punching

◯ ◯ ◯

◯ ◯-Δ State of worked

◯ ◯ ◯

◯ ◯-Δ surface

From the result of Table 2, it can be seen that excellent lubricity and anti-seizure property can be obtained if the ester compound is added even when sulfur type extreme pressure additives, organic zinc compound, calcium type additives are added each alone or in admixture. Further, it can also be seen that the lubricity tends to improve as the kinetic viscosity is higher. On the contrary, with reference to Table 3, it has been found that the lubricant 13 to lubricant 18 with addition of all of the sulfur type extreme pressure additives, organic zinc compound, calcium type additives, and ester compound had excellent lubricity and anti-seizure property which were comparable with or excellent over the chlorine type lubricants as apparent from comparison with Comparative Example 1 to Comparative Example 3.

Then, in the previous lubricity anti-seizing property test, since lubricants were prepared by adding each of the additives to the base oil 4 having a kinetic viscosity at 40° C. of 46 mm²/s, the workability in a case of using the base oil 5 to base oil 8 having lower kinetic viscosity was confirmed. The blending ratio in this case corresponded to that of the lubricant 14 having an intermediate blending amount among the lubricant 13 to lubricant 15 showing excellent lubricity or the like. Table 4 shows the result. In Table 4, numerical values other than those for the kinetic viscosity are indicated by % by weight, the kinetic viscosity is a kinetic viscosity at 40° C. being based on the unit of mm²/s.

TABLE 4 Lubricant Lubricant Lubricant Lubricant 19 20 21 22 Base oil 5 17 Base oil 6 17 Base oil 7 17 Base oil 8 17 a1 20 20 20 20 a2 20 20 20 20 b 20 20 20 20 c 20 20 20 20 d 3 3 3 3 Total 100 100 100 100 Sulfur content 14.02 14.02 14.02 14.02 Zinc content 1.78 1.78 1.78 1.78 Calcium content 3.04 3.04 3.04 3.04 Ester content 3.00 3.00 3.00 3.00 Kinetic viscosity 277 216 187 166 State of punching

State of worked surface

From the result of Table 4, it has been found that excellent lubricity and anti-seizure property were obtained also by using base oils of low kinetic viscosity so long as the sulfur type extreme pressure additives, organic zinc compound, calcium type additives, and ester type compound were added. However, since the kinetic viscosity is excessively high in this state, it will be apparent that this may give undesired effects in the cleaning and the coating steps also in view of the result of the previous cleaning property test.

(Kinetic Viscosity Control Test)

The lubricity and the anti-seizure property were evaluated after lowering the kinetic viscosity for enhancing the cleaning property. The result is shown in Table 5. Lubricant 14 was selected again as a typical example, and it was diluted with the base oil 7 of a low kinetic viscosity (kinetic viscosity at 40° C. of 10 mm²/s) to lower the kinetic viscosity. In Table 5, numerical values other than those for the kinetic viscosity are indicated by % by weight, and the kinetic viscosity is the kinetic viscosity at 40° C. based on the unit of mm²/s. Further, the condition and the method in this test, and the evaluation criterion were identical with those in the previous cleaning property test and the lubricity and the anti-seizure property test.

TABLE 5 Lubricant Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 14 Lubricant 5 10 15 20 25 50 14 Base oil 4 0.85 1.70 2.55 3.40 4.25 8.50 17 Base oil 7 95 90 85 80 75 50 a1 1.00 2.00 3.00 4.00 5.00 10 20 a2 1.00 2.00 3.00 4.00 5.00 10 20 b 1.00 2.00 3.00 4.00 5.00 10 20 c 1.00 2.00 3.00 4.00 5.00 10 20 d 0.15 0.30 0.45 0.60 0.75 1.50 3.00 Total 100 100 100 100 100 100 100 Sulfur 0.70 1.40 2.10 2.80 3.51 7.01 14.02 content Zinc 0.09 0.18 0.27 0.36 0.45 0.89 1.78 content Calcium 0.15 0.30 0.46 0.61 0.76 1.52 3.04 content Ester 0.15 0.30 0.45 0.60 0.75 1.50 3.00 content Kinetic 11 13 15 18 21 48 244 viscosity Surface ◯ ◯ ◯ ◯ ◯ Δ X evaluation State of Δ ◯

punching State of Δ ◯

worked surface

From the result of Table 5, it can be seen that excellent cleaning property was obtained after adding the sulfur type extremely pressure additives, the organic zinc compound, the calcium type additive, and the ester compound to the base oil for the lubricant so long as the kinetic viscosity at 40° C. was about 25 mm²/s or lower. Further, it can be seen that there is no substantial problem in the cleaning property when the kinetic viscosity at 40° C. is about 50 mm²/s or less. Accordingly, it can be seen that in a case where the kinetic viscosity at 40° C. is 40 mm²/s or less and, preferably, the kinetic viscosity at 40° C. is 30 mm²/s or lower, the lubricant at least shows good cleaning property and lessens negative effects on the coating step. The result also conforms with the result in Table 1.

Further, it can be seen that good or excellent workability is provided by adding the sulfur type extreme pressure additives, the organic zinc compound, the calcium type additives and the ester compound even when the kinetic viscosity is at a low level as described above. However, since the workability in Example 1 is somewhat poor, while working is possible with no significant problem even at a kinetic viscosity at 40° C. of about 5 mm²/s, it is preferred to control the kinetic viscosity at 40° C. to 10 mm²/s or more.

Further, from the results of Table 2 to Table 5, it can be seen that a preferable range of the composition is when (a) the sulfur content is from 0.5 to 10% by weight based on the entire amount of the lubricant, (b) the zinc content is from 0.05 to 1.0% by weight based on the entire amount of the lubricant, (c) the calcium content is from 0.1 to 2.0% by weight based on the entire amount of the lubricant and (d) the ester content is from 0.1 to 2.0% by weight based on the entire amount of the lubricant. In the kinetic viscosity control test described above, while the kinetic viscosity was controlled by diluting the lubricant 14 with the base oil 7 of low kinetic viscosity, the way of controlling the kinetic viscosity (combination of high viscosity and low viscosity) per se can vary within a range not departing from the gist of the invention and is not restricted to the test examples described above.

(Adaptability Test with Alkali Ion Water)

Further, for confining that the lubricant of the invention is suitable to cleaning with an alkali ion water, the following test was conducted selecting the cleaning liquid used upon cleaning Example 2, Example 4, Example 6, and Comparative Example 3 used in the tests described above as a typical example. At first, after filtering the an alkali ion water after cleaning to remove impurities, the alkali ion water was heated to 65° C. and put into a measuring cylinder each by 50 ml. Then, the measuring cylinder was stirred vigorously for 30 sec by 100 times and the amount of bubbling, time required for defoaming, and the time required for separation in this case were measured. The result is shown in Table 6.

TABLE 6 Comparative Example 2 Example 4 Example 6 Example 3 Amount of bubbling  3  4  4  5 (ml) Defoaming time (sec) 30 30 150 150 Separability (sec) 30 30 120 180 State of separation 0:6:4 0:1:9 0:1:9 0:3:7 layer (water:emulsion:oil)

From the result of Table 6, each of the examples result was excellent for each of the bubbling amount, the defoaming property and the separability over the chlorine type comparative example. Further, while the state of separated layer in Example 2 was somewhat inferior to that of Comparative Example 3, it can be seen that Example 4 and Example 6 are outstandingly excellent. It can be seen from the foregoing, that since the lubricant of the invention has better adaptability with the alkali ion water than that of the chlorine type lubricant, it is suitable to the cleaning with the alkali ion water. 

1. A lubricant for use in press working of a metal material having a non-chlorine type composition including a sulfur type extremely pressure additive, an organic zinc compound, a calcium type additive, and an ester compound are blended with a lubricant base oil, and have a kinetic viscosity from 5 to 50 mm²/s at 40° C.
 2. A lubricant according to claim 1, wherein the sulfur content is from 0.5 to 10% by weight based on the entire amount of the lubricant, the zinc content is from 0.05 to 1.0% by weight based on the entire amount of the lubricant, the calcium content is from 0.1 to 2.0% by weight based on the entire amount of the lubricant, and the ester content is from 0.1 to 2.0% by weight based on the entire amount of the lubricant.
 3. A lubricant according to claim 2, wherein the sulfur type extreme pressure additive is one or more members selected from the group consisting of sulfurized oils and fats, sulfurized fatty acids, sulfurized esters, sulfurized olefins, polysulfides, thiocarbamates, and sulfurized mineral oils.
 4. A lubricant according to claim 2, wherein the organic zinc compound is at least one of a zinc dialkyl dithiophosphate and/or a zinc dialkyl dithiocarbamate.
 5. A lubricant according to claim 2, wherein the calcium type additive-is one or more members selected from the group consisting of calcium sulfonate, calcium salicylate, and calcium phenate.
 6. A lubricant according to claim 2, wherein the calcium type additive-is a basic calcium sulfonate with a total base amount of 300 mgKOH/g or more.
 7. A lubricant according to claim 2, wherein the ester compound is at least one of a polyol ester and/or a complex ester.
 8. A lubricant according to claim 2, wherein the metal material is an anti-rust steel sheet.
 9. A lubricant according to claim 8, wherein the anti-rust steel sheet is an electrolytic zinc plated metal sheet.
 10. A lubricant according to claim 2 for working a metal material to be cleaned with an alkali ion water after the working.
 11. A lubricant according to claim 2 for working a metal material which is cleaned after the working and then applied with a coating treatment.
 12. A method of press working a metal material including a step of conducting working between a metal material and a tool including a lubricant which is of a non-chlorine composition comprising a sulfur type extreme pressure additive, an organic zinc compound, a calcium type additive, and an ester compound blended with a base oil and having a kinetic viscosity from 5 to 50 mm²/s at 40° C.
 13. A method of press working a metal material according to claim 12, wherein the sulfur content is from 0.5 to 10% by weight based on the entire amount of the lubricant, the zinc content is from 0.05 to 1.0% by weight based on the entire amount of the lubricant, the calcium content is from 0.1 to 2.0% by weight based on the entire amount of the lubricant, and the ester content is from 0.1 to 2.0% by weight based on the entire amount of the lubricant.
 14. A method of press working a metal material according to claim 13, wherein the metal material is an anti-rust steel sheet, a cleaning step of cleaning the anti-rust steel sheet subjected to press working with an alkali ion water and a coating step of coating a coating material to the surface of the anti-rust steel sheet that has been cleaned in the cleaning step.
 15. A method of press working a metal material according to claim 14, wherein the alkali ion water to be used in the cleaning step is heated to a temperature of 60 to 80° C. 